Experimental Study Of Donor Hearts Preserved In Beating Status With Continous Perfusion For Heart Transplantation

Part1. Establishing of animal model of preservation and transplantation in beating status donor heart of Bama miniature pigObjective::Based on our previous study about the preservation method of donor hearts in an empty beating status with mild hypothermic perfusion. we improved the beating preservation technique to completely avoid cardiac arrest and myocardial ischemia, keeping the donor hearts in beating status from procurement of hearts to transplants and assessing its efficacy for long-term preservation and feasibility for heart transplantation.Methods:16swine were preserved in beating status (group A, n=8, perfused continuously with normothemic blood) or in static cold storage (group B, n=8, stored in4℃histidine-tryptophan-ketoglutarate solutions) for8hours. Then the donor hearts were implanted either in beating or static status. During transplantation, the incidence of arrhythmia, time of anastomosis and cardiopulmonary bypass, dosage of inotropic drugs were recorded. Hemodynamics of left ventricule, cardiac output and Serum level of creatine kinase-MB were measured during transplantation. Myocardial ultrastructure were also observed.Results:Comparied with group B, the anastomotic time of group A was significantly longer, the cardiopulmonary bypass time was significantly shorter, the incidence of arrhythmia, dosage of cardiovascular-activity drugs and serum level of creatine kinase-MB were lower. After declamping for two hours and three and half an hours, the hemodynamics of left ventricular of group A was significantly better than group B. The myocardial ultrastructure of group A was superior to the group B.Conclusions:Preservation of donor hearts in beating status with continuous, normothemic, blood perfusion is an effective approach for long-term preservation and fits for heart transplantation. Part2. Function, metabolism and apoptosis of donor hearts preserved in beating status with continuous normothermic perfusionObjective:To investigate the protective efficacy of beating donor heart preservation with normothemic continuous perfusion by the cardiac function, myocardial metabolism and apoptosis of myocardiocyte.Methods:12Guangxi Bama miniature pig were randomly divided into two group: group A (n=6) and group B (n=6). The hearts of group A were procured in beating status with antegrade continuous perfusion continuous perfusion, and preserved in beating status at37℃for8hours; The hearts of group B were procured in staic status, which were arrested by the St.Thomas solution, and stored with antegrade continuous perfusion of hyperkalemia blood at29℃for8hours. During preservation of hearts, oxygen consumption of myocardium, serum level of CK-MB and cTn-I were test at preservation0.5hours,4hours and8hours. Then the hearts transplants were performed. Arfter the aortic declamping for3hours, the left ventricular hemodynamics were detected; the samples of myocadium were abtained for measurement the myocardial water content, malondialdehyde and ATP content of myocardium and cardiomyocyte apoptosis.Results:After preservation for0.5hours,4hours and8hours, the myocardial oxygen uptake of group A were significantly larger than the B group. In the two groups, serum levels of CK-MB and cTn-I were inreased with the preservation time prolonged, and there were not significant difference between the two groups. After declamping for3hours, the left ventricular hemodynamics of group A were significantly prior to the group B; myocardial water content in group A was slightly less than the group B; the light microscopy of group B showed obviously myocardial edema; myocardial ATP content in group A was significantly higher than group B; myocardial malondialdehyde content and quantity of cardiomyocyte apoptosis in group A was significantly lower than in group B.Conclusion:The normothemic continuous perfusion preservation of donor hearts in beating status is available for protection of cardiac function, improving myocardial metabolism and decreasing apoptosis of myocardiocyte during long-term preservation. Part3. Influence of hematocrit and saline on the efficacy of donor heart preserved in beating statusObjective:To study the influence of concentrations of saline and hematocrit of normothermic blood perfusion solution to the beating donor heart preservation.Methods:Twelve Guangxi Bama miniature pigs were randomly divided into two group: Group A (n=6), the concentrations of saline and hematocrit were at about156mmol/L and22%, respectively; Group B (n=6):the concentrations saline and hematocrit were at about146mmol/L and17%, respectively. During preservation, the heart beating rates and incidence of arrhythmia were recorded; at preservation of4hours and8hous, the hemodynamics of left ventricule were measured; after preservation for8hours, myocardial specimen were obtained to test myocardial ultrastructure and myocardial water content.Results:There was no difference in the heart beating rates and incidence of arrhythmia in the two groups. Comparison of group A to group B, the hemodynamics of left ventricule of4hours no significant difference in the two groups, but at8hours it was significantly difference at the letf ventricular systolic pressure (30.5±7.7vs17.9±4.5, P<0.05), maximal rates of increase of the left ventricular developing pressure (591±159vs283±60,P<0.05); the myocardial water content were80.5±0.4and81.4±0.5(P<0.05), respectively. The ultrastructure of group A were superior to the group B at the edema degree of sarcolemma and intact degree of mitochondria cristae.Conclusion:For normothermic blood perfusion solution, the properly increased the concentrations of saline and hematocrit can effectively attenuate myocardial edema and preserving cardiac function of long-term preserved beating donor heart.